First-trimester chorionic villus sampling: genetic analysis of 985 cases

Objective To investigate the value and safety of first-trimester chorionic villus sampling (CVS) in prenatal diagnosis. Methods This study retrospectively analyzed the clinical data of 985 cases undergoing CVS and prenatal diagnosis with karyotyping and fluorescence in situ hybridization (FISH) in the Department of Obstetrics and Gynecology of Peking University First Hospital from January 2012 to December 2017. The success rate of cell culture, indications for prenatal diagnosis, karyotyping results, and complications of CVS were described. Results Among the 985 cases, 970 (98.48%) underwent FISH and 893 (90.66%) received karyotyping, and 878 (89.14%) accepted both. After CVS, the success rate of cell culture was 96.64% (863/893). Abnormal ultrasonographic findings (42.64%, 420/985) were the most common indications for prenatal diagnosis. In this study, 181 cases of chromosomal abnormalities were detected, including numerical and structural abnormalities, accounting for 18.38% of all 985 cases. Those cases with abnormal ultrasonographic images had the highest detection rate of chromosomal abnormalities (31.90%, 134/420), followed by those with adverse pregnant history (11.83%, 20/169) and advanced maternal age (8.21%, 11/134). In addition, there was a discrepancy between karyotyping and FISH results, which might due to 16 cases of placental mosaicism and 13 cases of maternal cell contamination (MCC). Embryonic demises were reported in six cases (0.61%, 6/985), including four with chromosomal numerical abnormalities within four weeks after CVS. No other short- or long-term postoperative complications were found in the rest 979 cases (99.39%). Conclusions CVS in the first trimester is a safe and reliable invasive method for prenatal diagnosis, which can help to obtain an earlier diagnosis in a certain population such as those with abnormal ultrasonographic findings, thus improve the pertinence and efficiency of prenatal diagnosis. However, the potential influences of placental mosaicism and MCC on the diagnostic results should not be ignored. Key words: Chorionic villi sampling; Prenatal diagnosis; Chromosome aberrations; Pregnancy trimester, first